topas

topas [options] [interval [count]]

interval
    Specifies the time in seconds between screen updates. The default is 2 seconds.

count
    Specifies the number of updates to display before exiting. If not specified, topas runs indefinitely.

-C
    Displays detailed CPU statistics. This is often the default view.

-D
    Displays detailed disk I/O statistics, including I/O rate, transfer rate, and busy percentage per disk.

-M
    Displays detailed memory statistics, including physical memory, paging space, and filesystem cache usage.

-N
    Displays detailed network I/O statistics, showing data rates, packets, and errors per network adapter.

-P
    Displays detailed process statistics, similar to top, showing CPU usage, memory, and command names for individual processes.

-L
    Displays Logical Partition (LPAR) statistics, useful in virtualized AIX environments.

topas is a powerful and interactive real-time performance monitoring utility, primarily associated with IBM's AIX operating system. While topas is not a native Linux command, it serves a similar purpose to tools like top, htop, nmon, or perf on Linux, providing a comprehensive overview of system resource utilization.

It displays various performance metrics including CPU usage, memory consumption, disk I/O, network activity, and process statistics, often presented with ASCII graphical representations. Users can navigate through different views (e.g., processes, disks, networks) to drill down into specific areas of interest. topas is designed for system administrators to quickly identify performance bottlenecks and understand system behavior in a dynamic environment. Its ability to display historical data via topasrec further enhances its diagnostic capabilities.

topas is a standard performance monitoring utility specific to IBM AIX and is not a native or commonly available command on most Linux distributions. Linux users seeking similar comprehensive monitoring tools should consider nmon (which has a Linux port and provides similar capabilities), htop, perf, or a combination of standard utilities like top, vmstat, iostat, and sar.

topas integrates with the topasrec utility (on AIX) to record system performance data into binary files. These files can later be analyzed using tools like topasout or imported into graphical analysis tools, allowing for post-mortem analysis and trend identification of system performance over time.

The topas utility originated as a core performance monitoring tool within IBM's AIX operating system. It was developed to provide system administrators with a real-time, interactive view of system resources, similar to top on Unix-like systems but with a broader set of metrics and graphical capabilities.

Its design focuses on comprehensive data presentation, including CPU, memory, disk, and network I/O, alongside process details. Over the years, it has evolved within the AIX ecosystem to support newer hardware architectures and virtualization features, such as Logical Partitions (LPARs). While topas remains an AIX-specific utility, its comprehensive approach has influenced the development and adoption of similar tools like nmon in the broader Unix/Linux community.

top(1), htop(1), nmon(1), vmstat(8), iostat(1), sar(1), perf(1)